We are studying the DNA sequence organization, transcription, and evolutionary conservation of structural genes for proteins, and their neighboring DNA, from animal genomes. The major emphasis is on the silk fibroin gene. We are mapping repeated sequences which occur near the fibroin gene and elsewhere in the DNA. We are testing the degree to which the neighboring DNA is conserved in evolution by cloning fibroin gene regions from related animals and comparing their sequences by annealing techniques. We are also mapping the transcription of this DNA. We will also prepare clones of mRNA sequences abundant in mammalian liver and examine transcription of the corresponding genes in isolated nuclei.